1. Field of the Invention
This invention relates to a liquid composition, an ink-jet recording ink, an ink-jet recording ink set, an ink-jet recording process, a recording unit, an ink cartridge and an ink-jet recording apparatus. More particularly, it relates to an liquid composition, an ink-jet recording ink and an ink-jet recording ink set which are able to give a good print quality level, lessen color bleeding that may occur in forming color images and further achieve long-lifetime service for an ink-jet recording head making use of heat energy, and an ink-jet recording process, a recording unit, an ink cartridge and an ink-jet recording apparatus which make use of any of these.
2. Description of the Related Art
The ink-jet recording process makes it easy to provide compact apparatus, to achieve a low running cost and to form color images and is advantageous for the formation of color images. However, under circumstances where image are sought to have higher quality, it has some problems. For example, where different two kinds of inks are adjoiningly applied onto a recording medium, there is a problem that the inks may come mixed at color boundaries of these inks with each other to cause a phenomenon (bleeding) that makes the color images formed have a low quality level. In particular, such color mixing (color bleeding) at color boundaries between black ink and color inks may greatly affect image quality level to lower it. Accordingly, how to settle this problem is variously on study.
For example, as disclosed in Japanese Patent Application Laid-open No. H05-202328, U.S. Pat. No. 5,198,023 and Japanese Patent Application Laid-open No. H06-106841, a technique is proposed in which a first liquid containing a precipitant and a second liquid containing a colorant (coloring material) capable of forming precipitates by the aid of the precipitant are used in combination to control the color bleeding. Then, a polyvalent metal salt is disclosed as this precipitant, and a dye or the like having at least one carboxylic group is disclosed as the colorant capable of forming precipitates by the aid of the polyvalent metal salt. It is also disclosed that the first liquid may further contain a colorant. In such a case, the first liquid is also usable as an ink.
However, according to detailed studies made by the present inventors, the above background art has been found to have a problem to be resolved as stated below. For example, in order to prevent the color bleeding, a solution containing the polyvalent metal salt disclosed in Japanese Patent Application Laid-open No. H05-202328 is repeatedly ejected by a thermal ink-jet system, where a heater may come into wire break to disable the ejection of the polyvalent metal salt solution in some cases. This is presumed to be due to the following: Where an ink or liquid composition containing the polyvalent metal salt is overheated with a heater, anions constituting the polyvalent metal salt may unwantedly evaporate or break. As the result, cations (polyvalent metal ions) present in the vicinity of the heater increase in concentration to make the ink strongly alkaline, so that an outermost surface protective layer may melt which is formed of a metal such as tantalum and/or an oxide of the metal, as so presumed. To cope with this matter, the present inventors have made extensive studies on a liquid composition, or composition of inks, that is effective in preventing the color bleeding and also can keep the heater from its wire break to contribute to long-lifetime service of the recording head.